const hello = 'hello world'
const arr = [1, 2, 3, 4]
const obj = {
  name: 'Tom',
  age: 18,
  sex: 'boy'
}
console.log('数组：', arr);
console.log('对象：', obj);
arr.push(5)
obj.age = 19
console.log('数组：', arr);
console.log('对象：', obj);